The progress in medicine is inherently linked to the development of robust technologies for the detection of biomolecules. The biochip technology provides accurate, practical, and cost-effective systems for point of care diagnosis via quantification of the molecular complexes using colorimetric, fluorescence, or electrochemical methods. The future development of the biochip methods depends on further miniaturization. It is clear, furthermore, that the processing of readout from biochips based on light intensity is fundamentally limited by the relationship between the size of the individual spot and the wave-length of light. This places a limitation on the accuracy of optical readout from the nanochips and thus provides an argument for further development of electrical detection schemes. Such electrical detection should enable the biochip technology to break through into the nanometer region since the resolution of the readings would be determined, in principle, by the size of a single DNA molecule. The goal of this proposal is to develop experimental strategies for the electrical detection of single-nucleotide polymorphisms (SNPs) and sequence- specific DNA-binding proteins (e.g. TATA binding protein) at the single molecule level via monitoring of the electrical properties of DNA molecules modified with covalently attached Nile Blue (NB) in electrochemically controlled nanoscopic tunnel junctions. The key objective of the proposed studies is to determine whether disruption of the DNA -stack via a single-point mutation or a protein binding results in an analytically effectual decrease in electrical conductivity of the helix. Specifically, we plan to develop protocols for the imaging of NB modified DNA arrays with single-molecule resolution via electrochemically controlled scanning tunneling microscopy, EC-STM. We will also use EC-STM approach to detect single nucleotide polymorphisms and to detect TATA binding protein (TBP) at the single molecule level. Finally, we will use the electrical conductivity of the NB modified DNA helix interposed between two closely spaced gold electrodes as an analytical nano-device for the detection of TBP based on sequence-specific binding to DNA. The PI's developmental objective is to continue engagement in bio-medically related research projects. It is expect that the requested SC-3 support would increase PI's productivity and would allow PI to continue research program with graduate and undergraduate students at CSULB. The completion of a four year funding requested in this application should allow PI to become more competitive for major NIH/NSF grant support. This funding will ultimately support the research infrastructure sustaining PI's efforts to entice students with the excitement of science and to train them to become our future scientists and professionals. PUBLIC HEALTH RELEVANCE: The biochip technology provides accurate, practical, and cost-effective systems for point of care diagnosis. The future development of the biochip methods depends on further miniaturization. The goal of this proposal is to develop experimental strategies for the electrical detection of single-nucleotide polymorphisms (SNPs) and sequence-specific DNA-binding proteins (e.g. TATA binding protein) at the single molecule level. Demonstrating the feasibility of such detection is critically important in the development of DNA based nano-sensors.